Determination of trace amounts of anthracene in phenanthrene by derivative synchronous fluorescence spectrometry

Since ordinarily available phenanthrene contains impurities such as phenanthrenequinone and fluoranthene, it is difficult to determine anthracene by spectrofluorimetry directly. Trace amounts of anthracene in phenanthrene can, however, be selectively determined by using the 4th-derivative synchronous fluorescence intensity without interference of these impurities. In 5 mL of cyclohexane, 25 mg of the sample is dissolved. The synchronous fluorescence spectrum of the solution is measured with wavelength interval (Delta lambda) of 24 nm in the range of 360-395 nm. Trace amounts of anthracene in phenanthrene can be determined from the 4th-derivative intensity at 376 nm, which is obtained by computation of the synchronous fluorescence spectrum. By this method, anthracene can be determined simply and rapidly. The determination limit is 0.5 ppm.